CLI improvements

[Lyrth]

Some suggestions for Clue's command-line interface

• - flag in place of the filename to read Clue script from stdin (moved from CLI stdin/stdout stream improvements #132)
• --quiet, -q flag to suppress info messages from output; warnings and errors should both be piped to stderr (see above linked issue)
• Compiler flag for LL/ULL handling on non-LuaJIT targets, maybe accepts none, remove, warn, error.
• Treat --target as preset set of options that can be overridden by individual compiler flags. May have to expose more flags for the other settings that each target changes.